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'eLoran' Considered As Backup For ADS-B

Although global positioning system technology is advancing by
leaps and bounds, pilots shouldn't toss out their old Loran
receivers just yet. A British company's efforts to retain and
modify the system as a backup for GPS is receiving careful scrutiny
in the US, as well.

FCW.com reports Trinity House, a United Kingdom company that
provides maritime navigation aides throughout England, Wales, and
Gibraltar, issued a request for proposals earlier this month for an
enhanced long-range navigation system -- dubbed eLoran -- for
pilots.

The company points out that ground-based loran radio signals are
not as susceptible to jamming or disruptions that can
sometimes plague GPS satellites.

As Aero-News reported earlier this
year, several US organizations -- including the
Aircraft Owners and Pilots Assocation -- have called on the FAA to
retain loran transmitters now in place throughout the lower 48
states and sections of Alaska. Such a system is needed, AOPA says,
as a backup in the event the agency's proposed GPS-based Automatic
Dependant Surveillance-Broadcast system (ADS-B) goes down.

The UK's intent to pursue an eLoran backup system "sends a very
strong signal to the US to go ahead" with its own eLoran system,
said Aviation Management Associates consultant Mike Harrison.

Harrison, who recently co-authored a white paper advocating such
a backup to the FAA, notes the government admits GPS signals can be
jammed, possibly by terrorists. Two terrorism suspects arrested in
Atlanta earlier this year planned attacks against GPS, he
added.

Unintentional attacks can muck up GPS signals, as well. A report
by General Lighthouse Authorities of the UK notes GPS signals
covering a section of land 60 miles south of San Francisco, CA were
jammed for nearly a month in 2001, due to an amplified television
antenna near Moss Landing Harbor.

Signals are much stronger from eLoran systems, advocates say, so
they're less susceptible to jamming.

Furthermore, the Aviation Management report says the FAA could
implement such an eLoran program relatively cheaply, thanks in part
to the agency's foresight. The FAA has already invested $160
million to modernize existing Loran transmitters since 1997, so
bringing those stations up to eLoran standards could be done for
between $24 million and $27 million.